Try placing a section of poly tarp or plastic thats larger than your tent floor area under the shower tent & rubber mats, this will drain the water outside away from the shower tent, elimenates mud under your feet.
If the tent has ground pegs around the base then fold the section into a longer length & just wide enough to slide through between the pegs, bit like a slippery-slide , placed correct with the edges slightly turned up it becomes a drain to carry the water away from the tent area.
JC.
Very clever Jim. You're not just a pretty face hey!
BEETTTHHHH; you never told me I was; hey